VARIABLE FORCE SOLENOID VALVE CONTROL DEVICE OF AN AUTOMATIC TRANSMISSION FOR INCREASING AN AVAILABLE VOLTAGE RANGE AND IMPROVING CONVENIENCE AND RELIABILITY FOR THE CHANGE OF A CIRCUIT IN CHANGING SPECIFICATIONS BY DIRECTLY CURRENT-CONTROLLING THE VALVE

摘要

PURPOSE: A VFS(Variable Force Solenoid) valve control device of an automatic transmission is provided to improve control stability and reliability by directly current-controlling the VFS valve by comparing a reference current with an actual VFS valve drive current. CONSTITUTION: A VFS valve control device of an automatic transmission is composed of an MCU(Main Control Unit,100) analyzing various information about a vehicle by a set algorism and outputting a control signal for regulating duty pressure in a present shift level; a reference current generating unit(200) converting the control signal of the MCU into an analog signal and generating a reference current for driving a VFS valve by using a current source and a reset signal; a reset unit(300) discharging voltage charged in a condenser(C5) in the reference current generating unit to make the reference current generating unit form the reference current; a sample & hold unit(400) keeping stability of the signal by sampling and holding the reference current for driving the VFS valve applied from the reference current generating unit; a current detecting unit(500) detecting a driving current according to the driving of the VFS valve; a driving unit(600) comparing the reference current supplied from the sample & hold unit with the VFS valve driving current applied from the current detecting unit by a comparator(U4) having hysteresis and driving the VFS valve by generating upper and lower limit reference currents necessary for actual drive of the VFS valve; and a diagnosing unit(700) outputting a square-wave failure signal of the VFS valve into the MCU by comparing the reference current sent from the sample & hold unit with the VFS valve driving current applied from the current detecting unit.